Depending on the nature of the failure it might be possible to get the array up again, by re-creating the array with exactly the same parameters as they were created originally, specifying the members in the right sequence (sda2 missing sdb2 sdc2, although I'd re-look at /proc/mdstat after a reboot to see if the devices names are changed), adding a '--assume-clean' to let the raid manager know it should *not* recalculate any xor blocks.

If the data it important, you'd better create a low-level copy of the disk which is called sda, maybe the first slot. It is failing, and copying your data away from a raid array gives a larger stress to a disk than a one-pass low level copy. So the odds that sda will die during copying files from the array are bigger than that it will die during a low-level copy.